SELECT 
  cscart_ult_product_prices.product_id, 
  MIN(
    IF(
      cscart_ult_product_prices.percentage_discount = 0, 
      cscart_ult_product_prices.price, 
      cscart_ult_product_prices.price - (
        cscart_ult_product_prices.price * cscart_ult_product_prices.percentage_discount
      )/ 100
    )
  ) AS price 
FROM 
  cscart_ult_product_prices 
WHERE 
  cscart_ult_product_prices.product_id IN (
    36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 
    47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 
    57, 58, 59, 60, 62, 63, 64, 65, 67, 68, 
    69
  ) 
  AND cscart_ult_product_prices.lower_limit = 1 
  AND cscart_ult_product_prices.company_id = 1 
  AND cscart_ult_product_prices.usergroup_id IN (0, 0, 1) 
GROUP BY 
  cscart_ult_product_prices.product_id

Query time 0.00062

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "sort_key": "cscart_ult_product_prices.product_id",
      "temporary_table": {
        "table": {
          "table_name": "cscart_ult_product_prices",
          "access_type": "ALL",
          "possible_keys": [
            "usergroup",
            "product_id",
            "company_id",
            "lower_limit",
            "usergroup_id"
          ],
          "rows": 4,
          "filtered": 100,
          "attached_condition": "cscart_ult_product_prices.lower_limit = 1 and cscart_ult_product_prices.company_id = 1 and cscart_ult_product_prices.product_id in (36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,62,63,64,65,67,68,69) and cscart_ult_product_prices.usergroup_id in (0,0,1)"
        }
      }
    }
  }
}